1. Field of the Invention
This invention relates to devices for simultaneously destroying and replacing buried pipes and more particularly, to an apparatus for progressively bursting a gas, water, sewer or other underground utility pipe and simultaneously drawing a replacement pipe into position behind the migrating burst point of the pipe being replaced. In a preferred embodiment the apparatus is characterized by a specially-designed rod-pulling device which is typically fitted with a pair of in-line double-action hydraulic rod-driving members and situated in a manhole or excavation, at one end of the pipe to be replaced. A rod is extended from the rod-driving members of the rod-pulling device, through the pipe and is attached to a stored energy head disposed in a typically conventional, tapered bursting head typically fitted with multiple blades which initially engage the opposite end of the pipe, and a replacement pipe is removably attached to the bursting head. Under circumstances in which valves, concrete encasement, timbers or other obstructions are likely to be encountered by the bursting head in the pipe, a pneumatic hammer is typically spring-biased against the stored energy head. In typical operation, the rod-driving members of the rod-pulling device alternately and repeatedly grip, pull and release the rod and move to a new grip position on the rod, to continually draw the rod through the rod-pulling device. The rod pulls the stored energy head against the bursting head and thus, the bursting head against the pipe to be replaced as the pneumatic hammer is typically operated to repeatedly strike the stored energy head against the bursting head. The combined pulling action of the rod-pulling device and driving action of the hammer cause the bursting head to progressively cut and rupture the old pipe along the length thereof and break through any obstructions in the pipe, and simultaneously draw the replacement pipe into position behind the migrating burst point of the old pipe. A pair of springs fitted in the stored energy head is compressed and biases the stored energy head against the bursting head as the rod pulls against the stored energy head. As the hammer strikes the stored energy head against the bursting head, tension released by the springs augments the driving action of the hammer and assists the rod-pulling device and hammer in forcing the bursting head along the pipe. When obstructions are unlikely to be encountered by the bursting head, the rod-pull device can be used without the pneumatic hammer to pull the bursting head along the pipe.
2. Description of the Prior Art
Underground water, gas, sewer and other utility pipes typically require replacement after an extended period of use, frequently due to corrosion or damage to the pipes. Usually, digging trenches to expose the damaged pipes for replacement is undesirable since this frequently requires destruction of streets, sidewalks, parking lots or lawns, which is unsightly and expensive. To avoid these problems, various techniques and apparatuses have been devised to destroy the pipe in need of replacement and draw a new pipe into place without having to excavate trenches for the operation. Generally, the techniques involve excavating the ground at both ends of the pipe to be replaced and positioning a hydraulic pulling device of selected design in one of the excavations and a cutting tool at the opposite end of the pipe in the other excavation. A rod or cable is extended from the pulling device, through the pipe and attached to the cutting tool at the opposite end of the pipe. As the hydraulic pulling device is operated to pull the cutting tool against the pipe, a pneumatic hammer typically repeatedly strikes the cutting tool against the pipe, and the combined pulling action of the pulling device and stag action of the hammer on the cutting tool causes the tool to migrate and progressively cut and burst the pipe along the entire length of the pipe. A replacement pipe is typically attached to the cutting tool such that the replacement pipe is drawn into position behind the cutting tool as the cutting tool bursts the old pipe.
Many devices are known in the art for bursting an underground pipe and drawing a replacement pipe into position behind the bursted pipe. Some of these devices are detailed in U.S. Pat. No. 4,648,746; U.S. Pat. No. 4,693,404; U.S. Pat. No. 4,732,222; U.S. Pat. No. 4,738,565; U.S. Pat. No. 5,013,188; U.S. Pat. No. 5,127,481; U.S. Pat. No. 5,171,106; U.S. Pat. No. 5,207,533; U.S. Pat. No. 5,306,101; U.S. Pat. No. 5,482,404; U.S. Pat. No. 5,580,188; U.S. Pat. No. 5,749,677; and U.S. Pat. No. 5,782,311.
Various devices for pulling a cable or rod against a resistance are known in the art. Some of these devices are detailed in U.S. Pat. No. 3,266,776; U.S. Pat. No. 4,448,393; 4,456,226; U.S. Pat. No. 4,593,884; U.S. Pat. No. 4,615,509; U.S. Pat. No. 4,634,101; and U.S. Pat. No. 5,277,406. Other patents of interest include U.S. Pat. No. 2,044,483; U.S. Pat. No. 2,126,933; U.S. Pat. No. 2,889,135; U.S. Pat. No. 2,939,739; U.S. Pat. No. 3,094,312; U.S. Pat. No. 3,787,950; U.S. Pat. No. 3,834,668; U.S. Pat. No. 3,998,428; U.S. Pat. No. 4,030,183; U.S. Pat. No. 4,571,802; U.S. Pat. No. 5,112,070; and U.S. Pat. No. 5,208,967,
An object of this invention is to provide a new and improved apparatus for bursting and replacing underground pipes.
Another object of this invention is to provide a new and improved apparatus for quickly and effectively bursting and replacing a water, gas, sewer or other underground utility pipe without requiring digging of trenches to expose the pipe.
Still another object of this invention is to provide a pipe bursting and replacement apparatus including a typically conventional pipe-bursting head for progressively bursting an underground pipe to be replaced; a specially-designed hydraulic rod-pulling device which pulls the pipe bursting head along the pipe; and a typically conventional pneumatic hammer which simultaneously drives the pipe bursting head along the bursting pipe, particularly under circumstances in which significant obstructions are encountered by the bursting head in the pipe, and wherein a replacement pipe is typically removably attached to the bursting head and drawn into position behind the migrating burst point of the pipe being replaced.
Yet another object of this invention is to provide a new and improved apparatus for bursting and replacing underground utility pipes, which apparatus includes a rod or cable pulling device of selected design situated in a manhole or excavation adjacent to one end of a pipe to be replaced; a typically conventional pipe bursting head initially engage the opposite end of the pipe; a pull rod or cable extending from the rod or cable pulling device and through the pipe to be replaced, and attached to a stored energy head disposed in the pipe bursting head; a spring or springs fitted in the stored energy head for biasing the stored energy head against the pipe bursting head as the rod or cable pulling device pull the stored energy head against the bursting head and thus, the bursting head against the pipe; and a typically conventional pneumatic hammer engaging the stored energy head for repeatedly striking the stored energy head against the pipe bursting head as the rod-driving members alternately and repeatedly grip and pull the pull rod and the attached stored energy head against the bursting head and thus, the bursting head against the pipe, whereby tension released by the springs augments the driving effect of the hammer and assists the rod-pulling device and Her in forcing the bursting head along the pipe as the hammer repeatedly strikes the stored energy head against the bursting head and forces the bursting head though valves, concrete encasement, timbers and other obstructions in and around the pipe.
A still further object of this invention is to provide a hydraulic pulling device for pulling a bursting head along an underground utility pipe, characterized by a pair of in-line, double-action hydraulic rod-driving members mounted on a frame, which rod-driving members are fitted with respective rod-gripping elements which alternately and repeatedly grip a rod attached to the bursting head and pull the rod as the other rod-gripping element releases the rod and moves to a new grip position on the rod, to progressively pull the bursting head along the pipe and burst the pipe to facilitate installation of a replacement pipe.
These and other objects of the invention are provided in a new and improved device for replacing an underground gas, water, sewer or other utility pipe by progressively cutting and bursting the pipe and drawing a replacement pipe into position behind the migrating burst point of the pipe being replaced. In a preferred embodiment the apparatus is characterized by a specially-designed rod-pulling device which is typically fitted with a pair of in-line, double-action hydraulic rod-driving members each having a rod-gripping element, and the rod-pulling device is typically situated in a manhole or excavation, at one end of the pipe to be replaced. A pull rod is extended through the rod-driving members of the rod-pulling device and through the pipe, and is attached to a stored energy head disposed in a typically conventional, tapered bursting head typically fitted with multiple blades which initially engage the opposite end of the pipe, A typically conventional pneumatic hammer is typically spring-biased against the stored energy head and a replacement pipe is removably attached to the bursting head. In typical operation, the rod-driving members of the rod-pulling device repeatedly and alternately grip, pull and release the pull rod and move to a new gripping position on the pull rod, and the pull rod pulls the stored energy head against the bursting head and thus, the bursting head against the pipe to be replaced as the pneumatic hammer repeatedly strikes the stored energy head against the bursting head The combined pulling action of the rod-pulling device and driving action of the hammer cause the bursting head to migrate along the pipe and progressively cut and rapture the pipe, and draw the replacement pipe into position behind the migrating burst point of the old pipe. A spring or springs fitted in the stored energy head are compressed and bias the stored energy head against the bursting head as the rod-pulling device pulls the rod against the stored energy head. As the hammer strikes the stored energy head against the bursting head, tension released by the springs augments the driving action of the hammer and assists the rod-pulling device and hammer in forcing the bursting head along the pipe. The pneumatic hammer is typically used in combination with the rod-pulling device only under circumstances in which valves, concrete encasement, timbers or other significant obstruction is likely to be encountered by the bursting head in or around the pipe being replaced. When obstructions are unlikely to be encountered by the bursting head, the rod-pulling device can be used without the pneumatic hammer to pull the bursting head along the pipe.